Fibromyalgia (FM) is a disorder that is characterized by chronic, diffuse musculoskeletal pain and areas of exquisite sensitivity at specific "tender points." Little is known, however, regarding the (a) natural history of FM; (b) factors underlying pain threshold levels at tender as well as non-tender points; and (c) pain perception and psychosocial factors that distinguish between persons with FM who seek medical treatment for their symptoms and those who do not seek medical care. Moreover, knowledge regarding these issues has been impeded by the use of samples of FM patients seen at tertiary care centers. We propose to address these issues by performing longitudinal as well as cross-sectional comparisons of pain perception and psychosocial variables among three subject groups. These groups are: (a) 50 patients drawn from the UAB Rheumatology clinic who have sough medical treatment of FM; (b) 50 age-,education-, and gender-matched persons sampled from the Birmingham community who meet the American College Rheumatology criteria for FM but who have not sought medical care for their symptoms (FM non-patients); and (c) 50 matched healthy controls sampled from the Birmingham community. These subjects will be evaluated on several pain perception and psychosocial variables at an initial assessment and at six-month intervals thereafter for a period of 3 years. Health-care seeking behavior related to FM and other medical problems also will be assessed during the course of the study. In this manner, factors that distinguish persons with FM who either seek medical care or do no seek treatment will be identified by cross-sectional and by longitudinal analyses. Pain perception variables will include pain threshold levels and sensory discrimination and response bias parameters derived from subject's responses to pressure stimulation of tender and non-tender points (i.e., sensory decision theory analysis). Psychosocial variables will include measures of environmental and psychological distress, functional disability, historical factors, pain coping strategies, and self-efficacy beliefs. This study is unique in that its design and many of the pain perception and psychosocial variables that will be examined never have been used in previous FM studies. We will test 13 specific hypotheses. The results of these analyses will advance our understanding of the (a) factors underlying pain perception in FM; and (b) role that pain perception and psychosocial variables may play in the health-care seeking behavior of persons with FM, changes in these variables over time, and associations among these variables which may have important treatment implications.